Hey everyone at the amtat-bb!
I spent a good portion of the day sick in bed yesterday and only naturally got to thinking about quite a few things. I figured i'd pop on here and start asking questions. Here's some background information on my sat experience; my rig consists of a TH-F6A (handheld, not full-duplex) and an arrow antenna. I have been successfull at manually trakcing the ISS and AO-51, but I have been unsuccessful at making a contact. I went out to field day (in Oviedo Florida) and was able to check out the rig the LMARS club uses. This got me wondering about sat tracking software, the internals and what definition of "North" that is used.
I'm familiar with the IGRF (from my day job as a GIS guy) and was wondering if any of these apps use the IGRF for calculating magnetic declination: http://www.ngdc.noaa.gov/IAGA/vmod/igrf.html
I've thought about creating my own rotator and started wondering about the configuration used. When you buy a rotator and put it out in the yard, i'm guessing you have to orient the base 'correctly'. How is the base of a rotator usually aligned? Do you get a compass out and use local magnetic north (without compensating for the declination from the IGRF).
I'm still in learning mode and very new to the world of sat, so if these are really dumb questions, my apologies!
I am open to any reading materials you can suggest on the matter.
Joseph Armrbuster, KJ4JIO
Joseph, Check out this page: http://www.thecompassstore.com/decvar.html# There's a link on that page to plug in your Zip code and figure declination, or you can use the handy map on the main page. For Austin, the magic number is 4 degrees.
If I recall correctly (it's been a few years), I set the rotor control box to North, went up on the roof and rotated the *mast* until the ants pointed to magnetic north (using a compass). Note that the compass will read inaccurately if held near a metal mast. Then I rotated the mast a bit more so the ants were pointing about 4 degrees *West of magnetic North*.
That's the way I remember doing it.
Bill N5AB
On Aug 12, 2009, at 10:28 AM, Joseph Armbruster wrote:
Hey everyone at the amtat-bb!
I spent a good portion of the day sick in bed yesterday and only naturally got to thinking about quite a few things. I figured i'd pop on here and start asking questions. Here's some background information on my sat experience; my rig consists of a TH-F6A (handheld, not full-duplex) and an arrow antenna. I have been successfull at manually trakcing the ISS and AO-51, but I have been unsuccessful at making a contact. I went out to field day (in Oviedo Florida) and was able to check out the rig the LMARS club uses. This got me wondering about sat tracking software, the internals and what definition of "North" that is used.
I'm familiar with the IGRF (from my day job as a GIS guy) and was wondering if any of these apps use the IGRF for calculating magnetic declination: http://www.ngdc.noaa.gov/IAGA/vmod/igrf.html
I've thought about creating my own rotator and started wondering about the configuration used. When you buy a rotator and put it out in the yard, i'm guessing you have to orient the base 'correctly'. How is the base of a rotator usually aligned? Do you get a compass out and use local magnetic north (without compensating for the declination from the IGRF).
I'm still in learning mode and very new to the world of sat, so if these are really dumb questions, my apologies!
I am open to any reading materials you can suggest on the matter.
Joseph Armrbuster, KJ4JIO _______________________________________________ Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
One can also use Polaris (the North Star) at least in most of the northern hemisphere where it is visible. A long time ago, I went outside after dark and looked at how my house lined up with Polaris. In my case, it was a dead sight along the front or back side and the peak of the roof to Polaris. If it's not, you could use a protractor to determine the difference. I have done that, relative to the E/W lines of the side of the house, to point the TV antenna to 125 degrees toward the transmitter site for this area.
Jerry N0JY
Joseph, Check out this page: http://www.thecompassstore.com/decvar.html# There's a link on that page to plug in your Zip code and figure declination, or you can use the handy map on the main page. For Austin, the magic number is 4 degrees.
If I recall correctly (it's been a few years), I set the rotor control box to North, went up on the roof and rotated the *mast* until the ants pointed to magnetic north (using a compass). Note that the compass will read inaccurately if held near a metal mast. Then I rotated the mast a bit more so the ants were pointing about 4 degrees *West of magnetic North*.
That's the way I remember doing it.
Bill N5AB
The only problem using Polaris, or most any star for that matter, is that the only time you're going to see it is when it's too dark to go climbing up the roof or tower to adjust the antenna. I use the one star that is always visible during the day, the Sun. Most satellite tracking programs can tell you where the sun is (Az/El), or you can look it up on-line. Aim the rotor controller to those coordinates, and then adjust the antenna so the shadow falls directly down the antenna boom. Done. I find it's best done later in the afternoon, when the Sun is closer to the horizon, but any time will do except when it's directly overhead.
And, with most practical 2m/70cm antenna systems, this adjustment doesn't need to be up to NASA standards. As I am sure you know, hand-holding the Elk, anywhere in the general direction of North works pretty well in practice.
Greg KO6TH
Date: Wed, 12 Aug 2009 11:22:16 -0500 From: [email protected] To: [email protected] CC: [email protected] Subject: [amsat-bb] Re: rotator questions
One can also use Polaris (the North Star) at least in most of the northern hemisphere where it is visible. A long time ago, I went outside after dark and looked at how my house lined up with Polaris. In my case, it was a dead sight along the front or back side and the peak of the roof to Polaris. If it's not, you could use a protractor to determine the difference. I have done that, relative to the E/W lines of the side of the house, to point the TV antenna to 125 degrees toward the transmitter site for this area.
Jerry N0JY
Joseph, Check out this page: http://www.thecompassstore.com/decvar.html# There's a link on that page to plug in your Zip code and figure declination, or you can use the handy map on the main page. For Austin, the magic number is 4 degrees.
If I recall correctly (it's been a few years), I set the rotor control box to North, went up on the roof and rotated the *mast* until the ants pointed to magnetic north (using a compass). Note that the compass will read inaccurately if held near a metal mast. Then I rotated the mast a bit more so the ants were pointing about 4 degrees *West of magnetic North*.
That's the way I remember doing it.
Bill N5AB
Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
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How about aiming for maximum receiver noise? That should be even more accurate.
Greg Wrote: and then adjust the antenna so the shadow falls directly down the antenna boom.
Hi Nigel, G8IFF/W8IFF
You are right
Aiming the antenna for maximum receiver Sun noise is the best method because the antenna pattern can be affected by some squint angle and not be perfectly aligned with the boom but receiving Noise from the Sun in 2 meters and 70 cm implies a very high antenna gain and a very low overall receiving Noise Figure with a very low Antenna temperature.
By the way at microwave such as 2400 MHz it is possible to receive the Sun Noise using a modest dish diameter even when the Sun activity is low as actually with around 67 sfu at 2800 MHz (10.7 cm)
See here:
http://www.swpc.noaa.gov/ftpdir/indices/DSD.txt
I use this method with my 1.2 meter dish 27 dBi at 2400 MHz and an overall receiving Noise Figure of 1 dB equivalent to a Noise Temperature of 75 kelvin
With the above dish and receiver I actually get a Sun Noise of about 3.5 dB of (S+N)/N wich is easily readible on the S meter or better using an AC Voltmeter connected to the audio output of receiver.
Using a tracking program and aiming the dish for maximum Sun Noise it is possible to calibrate the AZ and EL angle of the control box for the through reference Sun position in the sky.
In addition repeating time to time the above procedure and knowing the actual Sun's sfu it is possible to monitor the state of healt of our receiving system.
By the way without an HEO satellite using 2400 MHz the above procedure is as well a little and interesting Radioastronomy exercise.
Best 73" de
i8CVS Domenico
----- Original Message ----- From: "Nigel Gunn G8IFF/W8IFF" [email protected] To: "Greg D." [email protected] Cc: [email protected]; [email protected] Sent: Thursday, August 13, 2009 2:17 PM Subject: [amsat-bb] Re: rotator questions
How about aiming for maximum receiver noise? That should be even more
accurate.
Greg Wrote: and then adjust the antenna so the shadow falls directly
down the antenna boom.
Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Using my 85cm offset feed dish on 2400-MHz with a 0.6 dBNF preamp (MK232A2), I could see about 1/2 s-unit of sun noise and a similar amount of ground noise when looking at nearby forest on the horizon. Comparing the sun shaddow on the dish vs. noise peak az-el readings would indicate how close the feed was to perfect boresight and alignment.
73, Ed - KL7UW
At 06:53 AM 8/13/2009, i8cvs wrote:
Hi Nigel, G8IFF/W8IFF
You are right
Aiming the antenna for maximum receiver Sun noise is the best method because the antenna pattern can be affected by some squint angle and not be perfectly aligned with the boom but receiving Noise from the Sun in 2 meters and 70 cm implies a very high antenna gain and a very low overall receiving Noise Figure with a very low Antenna temperature.
By the way at microwave such as 2400 MHz it is possible to receive the Sun Noise using a modest dish diameter even when the Sun activity is low as actually with around 67 sfu at 2800 MHz (10.7 cm)
See here:
http://www.swpc.noaa.gov/ftpdir/indices/DSD.txt
I use this method with my 1.2 meter dish 27 dBi at 2400 MHz and an overall receiving Noise Figure of 1 dB equivalent to a Noise Temperature of 75 kelvin
With the above dish and receiver I actually get a Sun Noise of about 3.5 dB of (S+N)/N wich is easily readible on the S meter or better using an AC Voltmeter connected to the audio output of receiver.
Using a tracking program and aiming the dish for maximum Sun Noise it is possible to calibrate the AZ and EL angle of the control box for the through reference Sun position in the sky.
In addition repeating time to time the above procedure and knowing the actual Sun's sfu it is possible to monitor the state of healt of our receiving system.
By the way without an HEO satellite using 2400 MHz the above procedure is as well a little and interesting Radioastronomy exercise.
Best 73" de
i8CVS Domenico
----- Original Message ----- From: "Nigel Gunn G8IFF/W8IFF" [email protected] To: "Greg D." [email protected] Cc: [email protected]; [email protected] Sent: Thursday, August 13, 2009 2:17 PM Subject: [amsat-bb] Re: rotator questions
How about aiming for maximum receiver noise? That should be even more
accurate.
Greg Wrote: and then adjust the antenna so the shadow falls directly
down the antenna boom.
Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Hi Nigel,
In theory, yes, the Sun is a known signal generator and can be used for this purpose, if you've got a good enough receive system to pick up the noise, and have the right test equipment to measure it. (Recall the original question started around an Elk-class antenna system, which I do not believe qualifies.)
Logistically, however, you are up on the roof or tower, screw drivers and wrenches in hand, and likely your instrumentation is not. How are you going to know when you have the right position? Using the shadow method - I actually use the shadow of my 2.4 ghz feed on the BBQ Grill dish as my guide - takes me all of a few seconds, and I'm consistently within a few degrees of perfect. Why not go with the easy method?
Greg KO6TH
Date: Thu, 13 Aug 2009 12:17:10 +0000 From: [email protected] To: [email protected] CC: [email protected]; [email protected]; [email protected] Subject: Re: [amsat-bb] Re: rotator questions
How about aiming for maximum receiver noise? That should be even more accurate.
Greg Wrote: and then adjust the antenna so the shadow falls directly down the antenna boom.
_________________________________________________________________ Get back to school stuff for them and cashback for you. http://www.bing.com/cashback?form=MSHYCB&publ=WLHMTAG&crea=TEXT_MSHY...
Good morning all...........well, interesting reading to say the least for me, being a noobie here chasing the birds. Now that I have my KLM's up for LEO's, and not having computer control of the cheap Radio Shack rotator, (which only travels about 355 degs stop to stop),I used the "close enough for govt work" or "horseshoe and hand grenade" approach. I ended up trying the compass method with inclination correction, and set it like that, but didnt seem right. So next used the "Dracula" method of driving a stake into the ground and waited till High Noon (1pm PDT) and looked at the shadow. Well, the compass method was as close and being I dont need exact degrees, this is where I am set. Course someday I hope to get the nice AZ-EL system up with computer control and then I will probably be more critical. Subject is interesting though about using the sun for a noise generator.
John W6ZKH
----- Original Message ----- From: "Greg D." [email protected] To: [email protected] Cc: [email protected], [email protected] Sent: Friday, August 14, 2009 10:41:00 PM GMT -08:00 US/Canada Pacific Subject: [amsat-bb] Re: rotator questions
Hi Nigel,
In theory, yes, the Sun is a known signal generator and can be used for this purpose, if you've got a good enough receive system to pick up the noise, and have the right test equipment to measure it. (Recall the original question started around an Elk-class antenna system, which I do not believe qualifies.)
Logistically, however, you are up on the roof or tower, screw drivers and wrenches in hand, and likely your instrumentation is not. How are you going to know when you have the right position? Using the shadow method - I actually use the shadow of my 2.4 ghz feed on the BBQ Grill dish as my guide - takes me all of a few seconds, and I'm consistently within a few degrees of perfect. Why not go with the easy method?
Greg KO6TH
Date: Thu, 13 Aug 2009 12:17:10 +0000 From: [email protected] To: [email protected] CC: [email protected]; [email protected]; [email protected] Subject: Re: [amsat-bb] Re: rotator questions
How about aiming for maximum receiver noise? That should be even more accurate.
Greg Wrote: and then adjust the antenna so the shadow falls directly down the antenna boom.
_________________________________________________________________ Get back to school stuff for them and cashback for you. http://www.bing.com/cashback?form=MSHYCB&publ=WLHMTAG&crea=TEXT_MSHY... _______________________________________________ Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Yes that's a good point, I'm not encouraging anyone to go on their roof at night, in fact I would heartily discourage it for the sake of safety. What I intended to mean was, I looked at Polaris at night, got the difference from the way my house/roof points, then took that protractor up to the roof during daylight to tweak the antennas. And as you also mention, a couple of degrees isn't going to make a lot of difference unless you are using some extremely narrow beamwidth antennas, so the fact that Polaris is actually about 2 degrees right of how my house points to the north is not of importance in my opinion. I positioned the antennas to point along the lines of the house and it works fine.
Jerry
The only problem using Polaris, or most any star for that matter, is that the only time you're going to see it is when it's too dark to go climbing up the roof or tower to adjust the antenna. I use the one star that is always visible during the day, the Sun.
Hi Joe and the group. IMHO when we get to discussing IGRF for mounting an antenna and rotator for amateur radio use, we are over thinking this issue. Now I must admit that I only have a 3 degree difference in EN19 which I completely ignore. I find there is too much magnetic QRM around here to get a good reading of MN and then correct for TN. The more sensitive the compass the harder to get a bearing. Well you get a bearing, but you know its dead wrong because you get a different reading my moving a few feet in any direction. So, unless you use the super desensitized 1/2" diameter compass on a Captain Canada Decoder Ring I find Google Earth pragmatically good enough.
Software such as SatPC32 and others allow you to make permanent corrections for AZ and EL changes or compensation for mounting the antenna a little off horizontal and true north, or changes that occur over time. A little slippage in any of the half dozen U-Bolts between the terra firma and the antenna beam during a windstorm can be corrected - U-bolts on the mast to rotator, rotator to boom, boom to the antenna saddle, the saddle to the beam. It's a wonder anything stays pointing to where you want it.
However, to contradict myself, I have been known, on occasion, to sight along the beam of my yagis to the Sun and use any number of the freeware Sun locator applications. Very handy on Field Days in remote locations. I've never found the Sun's RF useful for aligning antennas mainly because I've never heard the difference on UHF/VHF or S band even with preamps, but, maybe that hearing loss due to age :-)
73, Alan VE4YZ EN19kv AMSAT LM 2352 http://www.wincube.ca
Hey everyone at the amtat-bb!
I spent a good portion of the day sick in bed yesterday and only naturally got to thinking about quite a few things. I figured i'd pop on here and start asking questions. Here's some background information on my sat experience; my rig consists of a TH-F6A (handheld, not full-duplex) and an arrow antenna. I have been successfull at manually trakcing the ISS and AO-51, but I have been unsuccessful at making a contact. I went out to field day (in Oviedo Florida) and was able to check out the rig the LMARS club uses. This got me wondering about sat tracking software, the internals and what definition of "North" that is used.
I'm familiar with the IGRF (from my day job as a GIS guy) and was wondering if any of these apps use the IGRF for calculating magnetic declination: http://www.ngdc.noaa.gov/IAGA/vmod/igrf.html
I've thought about creating my own rotator and started wondering about the configuration used. When you buy a rotator and put it out in the yard, i'm guessing you have to orient the base 'correctly'. How is the base of a rotator usually aligned? Do you get a compass out and use local magnetic north (without compensating for the declination from the IGRF).
I'm still in learning mode and very new to the world of sat, so if these are really dumb questions, my apologies!
I am open to any reading materials you can suggest on the matter.
Joseph Armrbuster, KJ4JIO _______________________________________________ Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
_______________________________________________ Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Joseph, sorry to hear about your sickies.....hope it wasnt the Pig Flu.
First........there are NO such things as dumb questions, as that is the only way I learn is by asking them myself.
Secondly.........all directional data given by a tracking program is using TRUE NORTH, and in my case it is 13 deg/27' inclination. I dont know if you are looking at any tracking software or not, but the popular ones are Orbitron, Satscape, Nova and SatPC32, which is what I use.
Thirdly.....the setup you are using should have no problem working into AO-51, AO-27 or SO-50 using 5 watts and an Arrow. ISS is rarely on FM voice, but more used for APRS or Packet on 145.825mhz. KG6NUB near San Francisco runs 500 miliwatts and an Arrow and does fine. Do you have another downlink receiver you can use to see if you can hear yourself come back from the bird? That is the best route, but it can still be done quite nicely using half-duplex as you are now. Just takes abit more patience. Try and see if you can find someone nearby who is also using the satellites and that will help in the instruction.
I have only been on satellites a short time myself, but it is addictive as "coke" (coca-cola that is!). It is a truely amazing mode of operation.
My first setup was a "Armstrong" AZ-EL system on a tripod. I have now graduated to some crossed-yagi's that are fixed at 25 degrees elevation and rotated with a cheap Radio Shack rotor. The antennas are at 12 feet above ground. With this setup, I am able to work 90% of the passes, with direct overhead being the hardest, due to the null on the downlink. (see photo)
Good luck and also alot of information here on the BB, just go back in the archives.
73 de John W6ZKH DM06
----- Original Message ----- From: "Joseph Armbruster" [email protected] To: [email protected] Sent: Wednesday, August 12, 2009 8:28:48 AM GMT -08:00 US/Canada Pacific Subject: [amsat-bb] rotator questions
Hey everyone at the amtat-bb!
I spent a good portion of the day sick in bed yesterday and only naturally got to thinking about quite a few things. I figured i'd pop on here and start asking questions. Here's some background information on my sat experience; my rig consists of a TH-F6A (handheld, not full-duplex) and an arrow antenna. I have been successfull at manually trakcing the ISS and AO-51, but I have been unsuccessful at making a contact. I went out to field day (in Oviedo Florida) and was able to check out the rig the LMARS club uses. This got me wondering about sat tracking software, the internals and what definition of "North" that is used.
I'm familiar with the IGRF (from my day job as a GIS guy) and was wondering if any of these apps use the IGRF for calculating magnetic declination: http://www.ngdc.noaa.gov/IAGA/vmod/igrf.html
I've thought about creating my own rotator and started wondering about the configuration used. When you buy a rotator and put it out in the yard, i'm guessing you have to orient the base 'correctly'. How is the base of a rotator usually aligned? Do you get a compass out and use local magnetic north (without compensating for the declination from the IGRF).
I'm still in learning mode and very new to the world of sat, so if these are really dumb questions, my apologies!
I am open to any reading materials you can suggest on the matter.
Joseph Armrbuster, KJ4JIO _______________________________________________ Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
My 2 cents.
Use a handheld GPS to align, or refer to a map. Reason: the Arrow is not a small beamwidth antenna...don't put too much accuracy into alignment. Like tracking pennies on a million dollar contract. Case in point: I took a TV rotor into the unfinished attic of my house, taped it to a cross beam on the floor with duct tape, inserted a sawed off handle from a standard shovel, and taped the Arrow at 30 degrees elevation to the handle. Aligned the Arrow to North by going outside and referencing the North Star after sunset against the alignment of my roof longitudinal. Works like a charm.
Mark Lunday WD4ELG Hillsborough, NC - FM06kb [email protected] http://wd4elg.net http://wd4elg.blogspot.com
-----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Joseph Armbruster Sent: Wednesday, August 12, 2009 11:29 AM To: [email protected] Subject: [amsat-bb] rotator questions
Hey everyone at the amtat-bb!
I spent a good portion of the day sick in bed yesterday and only naturally got to thinking about quite a few things. I figured i'd pop on here and start asking questions. Here's some background information on my sat experience; my rig consists of a TH-F6A (handheld, not full-duplex) and an arrow antenna. I have been successfull at manually trakcing the ISS and AO-51, but I have been unsuccessful at making a contact. I went out to field day (in Oviedo Florida) and was able to check out the rig the LMARS club uses. This got me wondering about sat tracking software, the internals and what definition of "North" that is used.
I'm familiar with the IGRF (from my day job as a GIS guy) and was wondering if any of these apps use the IGRF for calculating magnetic declination: http://www.ngdc.noaa.gov/IAGA/vmod/igrf.html
I've thought about creating my own rotator and started wondering about the configuration used. When you buy a rotator and put it out in the yard, i'm guessing you have to orient the base 'correctly'. How is the base of a rotator usually aligned? Do you get a compass out and use local magnetic north (without compensating for the declination from the IGRF).
I'm still in learning mode and very new to the world of sat, so if these are really dumb questions, my apologies!
I am open to any reading materials you can suggest on the matter.
Joseph Armrbuster, KJ4JIO _______________________________________________ Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
participants (10)
-
Alan VE4YZ -
Bill Howell -
Edward Cole -
Greg D. -
i8cvs -
Joseph Armbruster -
Mark Lunday -
n0jy＠lavabit.com -
Nigel Gunn G8IFF/W8IFF -
w6zkh＠comcast.net